Assays are generally procedures for determining the presence, quantity, activity, and/or other properties or characteristics of components in a sample. In some cases, the samples to be assayed are complex, the components of interest within the samples—e.g., a nucleic acid, an enzyme, a virus, a bacterium—are only minor constituents of the samples, and the results of the assays are required quickly and/or for many samples.
Some current systems perform assays with the aid of droplets generated in droplet generators. Often, the droplet generators work by partitioning a sample into multiple droplets. The sample may be an aqueous sample that is contacted with a stream of oil fluid in such a way as to form a disperse phase of aqueous droplets in a continuous oil phase. In such systems, droplets with sample partitions are generated for storage in a droplet storage vessel, from which a sample can subsequently be processed (e.g., amplified in the case of PCR) and analyzed.
Due to the sensitivity of droplets to mechanical motion and accompanying shear forces, care is ordinarily taken in transporting droplets to a droplet storage vessel, or directing a droplet from the droplet generator to a processing station and subsequently a droplet reader. Improved droplet generation mechanisms would be of great benefit to biological and clinical assays that use droplet-based assays.